CN117673650A - High-wettability modified diaphragm and preparation method and application thereof - Google Patents

High-wettability modified diaphragm and preparation method and application thereof Download PDF

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CN117673650A
CN117673650A CN202211042078.0A CN202211042078A CN117673650A CN 117673650 A CN117673650 A CN 117673650A CN 202211042078 A CN202211042078 A CN 202211042078A CN 117673650 A CN117673650 A CN 117673650A
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monomer
diaphragm
modified
separator
irradiation
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赵金保
陈志强
张鹏
何争
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Xiamen University
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Xiamen University
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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Abstract

The invention discloses a high-wettability modified diaphragm, a preparation method and application thereof. The invention adopts the irradiation in-situ grafting technology, utilizes the high specific energy of the rays generated by a radiation source, uniformly grafts the monomer with the lyophile functional group on the surface and the inside of the holes of the porous membrane through in-situ grafting on the basis of ensuring the original basic characteristics and the appearance of the porous membrane as much as possible, improves the affinity between the membrane and the electrolyte on the one hand, thereby improving the energy efficiency of the lithium ion secondary battery, and on the other hand, provides commercial prospect for modifying the membrane on a large scale by utilizing the irradiation grafting technology to modify the membrane.

Description

High-wettability modified diaphragm and preparation method and application thereof
Technical Field
The invention relates to the field of polymer modified materials, in particular to a battery diaphragm.
Background
The lithium ion battery is used as a chemical power system with high energy density, high output voltage, no memory effect, excellent cycle performance and environmental friendliness, has good economic benefit, social benefit and strategic significance, is widely applied to various fields such as mobile communication, digital products and the like, and is most likely to become the most main power system in the fields of energy storage and electric automobiles.
In lithium ion batteries, the separator has the main function of preventing positive and negative electrode contact and allowing ion conduction, and is an important component of the lithium ion battery. Up to now, separators used in commercial lithium ion batteries are mainly polyolefin-based separator materials having a microporous structure, such as a single-layer or multi-layer film of Polypropylene (PE) or Polypropylene (PP). Because of the nature of the polymer itself, although polyolefin separators can provide adequate mechanical strength and chemical stability at ordinary temperatures, these polyolefin separators still have some drawbacks. The poor wettability of a common polyolefin separator in a traditional liquid electrolyte results in low liquid absorption capacity, thereby affecting the cycle life of a lithium ion battery. Accordingly, there is a need for improvements over existing diaphragms.
Disclosure of Invention
In order to solve the problems, the invention provides a high-wettability modified diaphragm, and a preparation method and application thereof. According to the invention, an irradiation in-situ grafting technology is adopted, the high specific energy of rays generated by a radiation source is utilized, on the basis of ensuring the original basic characteristics and morphology of the porous diaphragm as much as possible, the in-situ grafting is adopted to uniformly graft the lyophilic monomer on the surface and the inside of the holes of the porous diaphragm, the effective contact between ions and the monomer is realized by modifying on an ion transmission path, and the wettability of the diaphragm and the electrolyte is improved by good affinity between the lyophilic monomer and the electrolyte.
One of the technical schemes adopted for solving the technical problems is as follows:
a modified separator of high wettability, the modified separator having a lyophilic monomer grafted to the surface and/or pores of its separator substrate, the lyophilic monomer having a lyophilic functional group. The modified diaphragm is prepared by introducing a lyophile monomer with lyophile functional groups on the surface and/or holes of a diaphragm substrate by adopting an irradiation grafting technology.
The lyophilic monomer is derived from a compound having an unsaturated bond group and containing a functional group having similar compatibility with the electrolyte.
The lyophile monomers, i.e., compounds having lyophile functional groups, also contain double bond/epoxy functional groups that can be radiation initiated to polymerize, such as vinyl, propenyl, and the like. For example, the lyophilic monomer may include one or more of small molecule ether monomers such as isobutyl vinyl ether, octadecyl vinyl ether, and poly (ethylene glycol) diacrylate (mn=250, 400, 700, etc.), and other lyophilic monomers containing lyophilic functional groups such as methyl methacrylate, methyl acrylate, acrylonitrile, 2,4,6, 8-tetramethyl-2, 4,6, 8-tetravinyl cyclotetrasiloxane, etc. But are not limited to, the above compounds.
The separator substrate is, for example, a polyolefin-based porous polymer film such as polypropylene or a single-layer or multi-layer composite film of polypropylene, or one or more of nonwoven fabric, polyethylene oxide, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride-hexafluoropropylene copolymer, polyacryl alcohol or polyimide, and a blended, copolymerized polymer derived from the above polymer materials.
The high-wettability modified diaphragm can be prepared by the following preparation method.
The second technical scheme adopted by the invention for solving the technical problems is as follows:
a preparation method of a high-wettability modified diaphragm comprises the steps of mixing a diaphragm substrate with a lyophilic monomer or an organic solution of the lyophilic monomer, and grafting the lyophilic monomer to the diaphragm substrate through irradiation grafting.
The method specifically comprises the following steps:
(1) Preparing an organic solution of a lyophile monomer: adding a lyophile monomer into an organic solvent outside an irradiation field, and stirring at the speed of 450-550 r/min for 5.5-6.5 h to obtain an organic solution of the lyophile monomer with the mass fraction of 10-100%; when the organic solvent is 0, that is, the organic solvent is not added, the lyophilic monomer itself may be obtained, and the obtained solution may be referred to as an organic solution of 100% by mass of the lyophilic monomer.
(2) Cleaning and drying the diaphragm substrate: washing the diaphragm substrate with acetone and drying at 55-65 deg.c for 5.5-6.5 hr;
(3) Performing irradiation grafting by adopting one of a co-irradiation grafting reaction, a pre-irradiation grafting reaction and a peroxidation grafting reaction, wherein the irradiation dose is 10-200 KGy;
(4) Cleaning and drying after irradiation grafting is completed: and (3) cleaning the modified diaphragm obtained in the step (3) by using ethanol, and drying at 55-65 ℃ for 5.5-6.5 hours to obtain the high-wettability modified diaphragm after drying.
The irradiation grafting method is one of a pre-irradiation grafting method, a co-irradiation grafting method or a peroxidation method. The pre-irradiation grafting process includes irradiating the diaphragm to produce stable falling free radical and grafting the falling free radical with air eliminating monomer at room temperature; the co-irradiation grafting method is to irradiate the diaphragm under the condition that the diaphragm is kept in direct contact with the monomer; the peroxidation method is to pre-irradiate the membrane substrate in an oxygen atmosphere and then graft the membrane substrate with a monomer. Specifically:
the co-irradiation grafting method comprises the following steps: immersing the membrane substrate treated in the step (2) in a lyophile monomer or an organic solution of the lyophile monomer, sealing, introducing inert gas argon to remove dissolved oxygen (polymerization inhibition), and then performing co-irradiation grafting reaction by a radiation source.
The pre-irradiation grafting method comprises the following steps: pre-irradiating the membrane substrate treated in the step (2) under argon atmosphere, and then placing the membrane substrate in a lyophile monomer or an organic solution of the lyophile monomer for grafting reaction;
the peroxidation method comprises the following steps: and (3) pre-irradiating the membrane substrate treated in the step (2) in an oxygen atmosphere, and then placing the membrane substrate in a lyophile monomer or an organic solution of the lyophile monomer for grafting reaction.
The organic solvent for dissolving the affinity group-containing monomer compound, that is, the lyophilic monomer is some small molecule alcohols, for example, methanol, ethanol, isopropanol, ethyl propanol, n-butanol, isobutanol, t-butanol, etc.; or other small molecule solvents such as acetone, chloroform, ethyl acetate, etc.
The radiation source for irradiation grafting comprises one of radioactive rays, a radiation source for acceleration supply and a neutron source.
Further, the radioactive rays include 1 of alpha rays, beta rays and gamma rays, wherein the radioactive source of the alpha rays is 241 Am、 239 Pu and 235 the radiation source of U and beta rays is 3 H、 14 C and C 90 One of Sr and gamma-ray radiation source is 60 Co、 137 Cs and 110 one of Sn.
Further, the radiation source provided by the acceleration includes one of an electron accelerator electron source and a heavy charged particle source.
Further, the neutron source includes one of an isotope neutron source, an accelerator neutron source, and a reactor neutron source.
The irradiation dose in the step (3) is preferably 10 to 100KGy, and more preferably 10 to 30KGy for the radiation resistance and due effectiveness of the separator substrate.
The lyophilic monomer and the separator substrate are as described above.
The third technical scheme adopted by the invention for solving the technical problems is as follows:
use of a modified separator with high wettability in a battery. Preferably, the battery is a lithium ion secondary battery.
The fourth technical scheme adopted for solving the technical problems is as follows:
a battery comprises a positive electrode material and a negative electrode material, wherein the high-wettability modified diaphragm is arranged between the positive electrode material and the negative electrode material. Specifically, the battery is a lithium battery; more specifically, the battery is a lithium ion secondary battery.
The positive electrode active material of the positive electrode material can be usually a compound Li capable of reversibly occluding and releasing (intercalating and deintercalating) lithium ions x MO 2 Or Li (lithium) y M 2 O 4 (wherein M is a transition metal, x is 0.ltoreq.1, y is 0.ltoreq.2), a lithium-containing composite oxide represented by the formula, a spinel-like oxide, a metal chalcogenide having a layered structure, an olivine structure, or the like.
The positive electrode active material may be LiCoO 2 Isolithium cobalt oxide, liMn 2 O 4 Equal lithium manganese oxide, liNiO 2 Equal lithium nickel oxide, li 4/3 Ti 5/3 O 4 Equal lithium titanium oxide, lithium manganese nickel composite oxide, lithium manganese nickel cobalt composite oxide, and lithium manganese nickel cobalt composite oxide having LiMPO 4 (m=fe, mn, ni) olivine-type crystalline structure material.
Lithium-containing composite oxides having a layered structure or spinel structure are preferable as the positive electrode active material, liCoO 2 、LiMn 2 O 4 、LiNiO 2 、LiNi 1/2 Mn 1/2 O 2 Lithium manganese nickel composite oxide represented by the same, and LiNi l/3 Mn 1/3 Co 1/3 O 2 、LiNi 0.6 Mn 0.2 Co 0.2 O 2 Or the like, or LiNi 1-x-y-z Co x Al y Mg z O 2 (wherein, x is more than or equal to 0 and less than or equal to 1, y is more than or equal to 0 and less than or equal to 0.1, z is more than or equal to 0 and less than or equal to 0.1, and 0 is more than or equal to 1-x-y-z is more than or equal to 1). In addition, some of the constituent elements in the above-described lithium-containing composite oxide are also included in the lithium-containing composite oxide, and the like, which is substituted with an additive element such as Ge, ti, zr, mg, al, mo, sn.
These positive electrode active materials may be used alone or in combination of 1 or 2 or more. For example, by using a layered lithium-containing composite oxide and a spinel-structured lithium-containing composite oxide together, both of a large capacity and an improvement in safety can be achieved.
For constituting a positive electrode of a nonaqueous electrolyte secondary battery, for example, a conductive auxiliary agent such as carbon black or acetylene black, or an adhesive such as polyvinylidene fluoride or polyethylene oxide is appropriately added to the positive electrode active material, and a positive electrode mixture is prepared and applied to a belt-shaped molded body having a current collector such as aluminum foil as a core material. However, the method for producing the positive electrode is not limited to the above example.
The negative electrode materials commonly used in lithium ion batteries can be used in the present invention. As the negative electrode active material of the negative electrode, a compound capable of inserting and extracting lithium metal or lithium can be used. Various materials such as alloys or oxides of aluminum, silicon, tin, and the like, carbon materials, and the like can be used as the anode active material. The oxide may be titanium dioxide, etc., and the carbon material may be graphite, pyrolytic carbon, coke, vitreous carbon, a fired body of an organic polymer compound, mesophase carbon microbeads, etc.
For example, a conductive additive such as carbon black or acetylene black, or a binder such as polyvinylidene fluoride or polyethylene oxide is appropriately added to the negative electrode active material to prepare a negative electrode mixture, which is applied to a belt-shaped molded body having a current collector such as copper foil as a core material. However, the method of manufacturing the negative electrode is not limited to the above example.
In the nonaqueous electrolyte secondary battery provided by the present invention, a nonaqueous solvent (organic solvent) is used as the nonaqueous electrolyte. Nonaqueous solvents include carbonates, ethers, and the like.
The carbonates include cyclic carbonates and chain carbonates, and examples of the cyclic carbonates include ethylene carbonate, propylene carbonate, butylene carbonate, gamma-butyrolactone, and thioesters (ethylene glycol sulfides, etc.). Examples of the chain carbonates include polar chain carbonates having low viscosity typified by dimethyl carbonate, diethyl carbonate, and methylethyl carbonate, and aliphatic branched carbonates. The mixed solvent of a cyclic carbonate (particularly, ethylene carbonate) and a chain carbonate is particularly preferable. Examples of the ethers include dimethyl ether Tetraglycol (TEGDME), ethylene glycol dimethyl ether (DME), and 1, 3-Dioxolane (DOL).
In addition, in addition to the nonaqueous solvent, a chain alkyl ester such as methyl propionate and a chain phosphotriester such as trimethyl phosphate may be used; nitrile solvents such as 3-methoxypropionitrile; non-aqueous solvents (organic solvents) such as branched compounds having an ether bond, represented by dendrimers.
In addition, a fluorine-based solvent may be used. Examples of the fluorine-based solvent include H (CF 2 ) 2 OCH 3 、C 4 F 9 OCH 3 、H(CF 2 ) 2 OCH 2 CH 3 、H(CF 2 ) 2 OCH 2 CF 3 、H(CF 2 ) 2 CH 2 O(CF 2 ) 2 H, etc., or CF 3 CHFCF 2 OCH 3 、CF 3 CHFCF 2 OCH 2 CH 3 (perfluoroalkyl) alkyl ethers of equilinear structure, namely 2-trifluoromethyl hexafluoropropyl methyl ether, 2-trifluoromethyl hexafluoropropyl ethyl ether, 2-trifluoromethyl hexafluoropropyl propyl ether, 3-trifluoromethyl octafluorobutyl methyl ether, 3-trifluoromethyl octafluorobutyl ethyl ether 3-trifluoromethyl octafluorobutyl propyl ether, 4-trifluoromethyl decafluoropentyl methyl ether, 4-trifluoromethyl decafluoropentyl ethyl ether, 4-trifluoromethyl decafluoropentyl propyl ether 5-trifluoromethyl dodecafluorohexyl methyl ether, 5-trifluoromethyl dodecafluorohexyl propyl ether, 6-trifluoromethyl tetradecyl fluoroheptyl methyl ether, 6-trifluoromethyl tetradecyl fluoroheptyl ethyl ether, 6-trifluoromethyl tetradecyl fluoroheptyl propyl ether, 7-trifluoromethyl hexadecyl fluorooctyl methyl ether, 7-trifluoromethyl hexadecyl fluorooctyl ethyl ether, 7-trifluoromethyl hexadecyl fluorooctyl propyl ether, and the like.
In addition, the above-mentioned iso (perfluoroalkyl) alkyl ether may be used in combination with the above-mentioned linear structure (perfluoroalkyl) alkyl ether.
As the electrolyte salt used in the nonaqueous electrolytic solution, lithium perchlorate, organoboron lithium salt, lithium salt of fluorine-containing compound, lithium salt such as lithium imide salt, and the like are preferable.
Examples of such electrolyte salts include LiClO 4 、LiPF 6 、LiBF 4 、LiAsF 6 、LiSbF 6 、LiCF 3 SO 3 、LiCF 3 CO 2 、LiC 2 F 4 (SO 3 ) 2 、LiN(C 2 F 5 SO 2 ) 2 、LiC(CF 3 SO 2 ) 3 、LiC n F 2n+1 SO 3 (n≥2)、LiN(RfOSO 2 ) 2 (wherein Rf isFluoroalkyl), and the like. Among these lithium salts, fluorine-containing organolithium salts are particularly preferable. The fluorine-containing organolithium salt is highly anionic and easily separated into ions, and is easily dissolved in a nonaqueous electrolytic solution.
The concentration of the lithium salt electrolyte in the nonaqueous electrolytic solution is, for example, preferably 0.3mol/L or more (mol/L) or more, more preferably 0.7mol/L or more, preferably 1.7mol/L or less, and still more preferably 1.2mol/L or less. When the concentration of the electrolyte lithium salt is too low, the ionic conductivity is too low, and when it is too high, there is a concern that the electrolyte salt which is not completely dissolved is precipitated.
In addition, various additives that can improve the performance of a battery using the nonaqueous electrolyte may be added to the nonaqueous electrolyte solution, and the nonaqueous electrolyte solution is not particularly limited.
The electrolyte of the battery also contains a lyophilic polymer monomer, wherein the polymer monomer is a monomer with vinyl and propenyl double-bond functional groups or epoxy functional groups, and comprises at least one of acrylic ester, acrylonitrile, methoxy acrylic ester, acrylamide, 2-acrylamide-2-methylpropanesulfonic acid, glycidyl methacrylate, ethylene carbonate, propylene carbonate, ethylene oxide, acrylic acid, styrene, fluoride, phosphazene, siloxane and acetate. But are not limited to, the above compounds.
The equipment, reagents, processes, parameters, etc. according to the present invention are conventional equipment, reagents, processes, parameters, etc. unless otherwise specified, and are not exemplified.
All ranges recited herein are inclusive of all point values within the range.
In the invention, the normal temperature and the room temperature, namely the normal ambient temperature, can be 10-30 ℃.
Compared with the background technology, the technical proposal has the following advantages:
1. according to the invention, the monomer with the lyophilic functional group is introduced into the diaphragm substrate, and the affinity between the diaphragm and the electrolyte can be greatly improved by utilizing a similar compatibility principle, so that the conduction of lithium ions is promoted, and the energy efficiency of the battery is effectively improved.
2. According to the invention, the lyophilic monomer can be directly introduced into the porous diaphragm from the molecular chain angle through the irradiation grafting method, the basic shape of the diaphragm is not changed, the process operation is simple, no additional process is needed, and the commercial production is facilitated.
Drawings
FIG. 1 is an infrared spectrum of the modified polypropylene separator and the general commercial polypropylene separator prepared in examples 1 to 3.
FIG. 2 is a scanning electron micrograph of a plane and a section of a modified polypropylene separator and a spectrometer elemental analysis photograph (upper: plane, lower: section), respectively.
FIG. 3 is a comparison of electrolyte wettability of the modified polypropylene separator obtained in example 1 with that of a general commercial polypropylene separator (left: commercial polypropylene separator, right: modified polypropylene separator of example 1).
Fig. 4 is a cycle performance comparison of the battery obtained in example 11 and comparative example 1.
Detailed Description
The invention is further described below with reference to the drawings and examples.
Example 1
Preparing a lyophilic modified diaphragm: 10g of poly (ethylene glycol) diacrylate (M n =250) was added to 90g of absolute ethanol and stirred at 500r/min for 6 hours to obtain an ethanol solution of poly (ethylene glycol) diacrylate with a mass fraction of 10%. The polypropylene (PP) membrane was washed with acetone and dried at 60 ℃ for 6 hours, then the polypropylene membrane was immersed in an ethanol solution of poly (ethylene glycol) diacrylate and sealed, and the inert gas argon was introduced to remove dissolved oxygen therein (polymerization inhibition). The material is placed in a radiation field and irradiated by gamma rays, and the irradiation dose is 10kGy. After the irradiation, the irradiated polypropylene separator was rinsed with a large amount of ethanol to remove unreacted monomers and homopolymers. And then drying the membrane for 6 hours at 60 ℃ to obtain the modified polypropylene membrane after drying.
Example 2
Preparing a lyophilic modified diaphragm: 20g of poly (ethylene glycol) diacrylate (M n =250) into 80g of absolute ethanol at a rate of 500r/minStirring for 6h to obtain an ethanol solution of 20% by mass of poly (ethylene glycol) diacrylate. The polypropylene separator was washed with acetone and dried at 60 ℃ for 6h. Then, the polypropylene diaphragm is soaked in ethanol solution of poly (ethylene glycol) diacrylate and sealed, and inert gas argon is introduced to remove dissolved oxygen (polymerization inhibition). The material is placed in a radiation field and irradiated by gamma rays, and the irradiation dose is 10kGy. After the irradiation, the irradiated polypropylene separator was rinsed with a large amount of ethanol to remove unreacted monomers and homopolymers. And then drying the membrane for 6 hours at 60 ℃ to obtain the modified polypropylene membrane after drying.
Example 3
Preparing a lyophilic modified diaphragm: 30g of poly (ethylene glycol) diacrylate (M n =250) was added to 70g of absolute ethanol and stirred at 500r/min for 6 hours to obtain an ethanol solution of poly (ethylene glycol) diacrylate with a mass fraction of 30%. The polypropylene separator was washed with acetone and dried at 60 ℃ for 6h. Then, the polypropylene diaphragm is soaked in ethanol solution of poly (ethylene glycol) diacrylate and sealed, and inert gas argon is introduced to remove dissolved oxygen (polymerization inhibition). The material is placed in a radiation field and irradiated by gamma rays, and the irradiation dose is 10kGy. After the irradiation, the irradiated polypropylene separator was rinsed with a large amount of ethanol to remove unreacted monomers and homopolymers. And then drying the membrane for 6 hours at 60 ℃ to obtain the modified polypropylene membrane after drying.
FIG. 1 is an infrared spectrum of a modified polypropylene separator and a general commercial polypropylene separator prepared in examples 1 to 3. The modified polypropylene separator showed a plurality of distinct characteristic peaks, one of which was 1740cm, compared with the conventional commercial polypropylene separator -1 The c=o stretching vibration peak of (c=o) can determine that the lyophilic monomer has been successfully grafted onto the polypropylene separator.
Fig. 2 is a scanning electron micrograph and a spectroscopy elemental analysis photograph of a plane and a section of the modified polypropylene separator, respectively. From fig. 2, it can be seen that the element C, O is uniformly distributed on the surface of the modified polypropylene separator and the inside thereof, whereby it can be judged that the lyophilic monomer is successfully grafted on the ion transport channel.
The membrane wicking was calculated according to the following formula:
imbibition ratio= (post-imbibition membrane mass-pre-imbibition membrane mass)/pre-imbibition membrane mass
The modified polypropylene membrane prepared in example 1 has a liquid absorption rate of 80%, and the common commercial polypropylene membrane is only 45%, which shows that the electrolyte adsorption capacity is obviously improved after the lyophilic monomer is grafted on the membrane.
The better electrolyte adsorption capacity of the modified polypropylene diaphragm obtained by the invention can be intuitively shown in fig. 3, wherein the left side of the fig. 3 is a photograph of the commercial polypropylene diaphragm soaked in the electrolyte, and the right side of the fig. 3 is a photograph of the modified polypropylene diaphragm soaked in the electrolyte, which shows that the electrolyte adsorption capacity of the modified polypropylene diaphragm obtained by the invention is obviously better than that of the commercial polypropylene diaphragm.
Example 4
Preparing a lyophilic modified diaphragm: 20g of poly (ethylene glycol) diacrylate (M n =250) was added to 80g of absolute ethanol and stirred at 500r/min for 6 hours to obtain an ethanol solution of poly (ethylene glycol) diacrylate with a mass fraction of 20%. The polypropylene separator was washed with acetone and dried at 60 ℃ for 6h. Then, the polypropylene diaphragm is soaked in ethanol solution of poly (ethylene glycol) diacrylate and sealed, and inert gas argon is introduced to remove dissolved oxygen (polymerization inhibition). The material is placed in a radiation field and irradiated by gamma rays, and the irradiation dose is 100kGy. After the irradiation, the irradiated polypropylene separator was rinsed with a large amount of ethanol to remove unreacted monomers and homopolymers. And then drying the membrane for 6 hours at 60 ℃ to obtain the modified polypropylene membrane after drying.
Example 5
Preparing a lyophilic modified diaphragm: 20g of poly (ethylene glycol) diacrylate (M n =250) was added to 80g of absolute ethanol and stirred at 500r/min for 6 hours to obtain an ethanol solution of poly (ethylene glycol) diacrylate with a mass fraction of 20%. The polypropylene separator was washed with acetone and dried at 60 ℃ for 6h. ThenThe polypropylene diaphragm is soaked in ethanol solution of poly (ethylene glycol) diacrylate and sealed, and inert gas argon is introduced to remove dissolved oxygen (polymerization inhibition). The material is placed in a radiation field and irradiated by gamma rays, and the irradiation dose is 80kGy. After the irradiation, the irradiated polypropylene separator was rinsed with a large amount of ethanol to remove unreacted monomers and homopolymers. And then drying the membrane for 6 hours at 60 ℃ to obtain the modified polypropylene membrane after drying.
Example 6
Preparing a lyophilic modified diaphragm: 20g of methyl methacrylate was added to 80g of absolute ethanol outside the irradiation field, and stirred at a speed of 500r/min for 6 hours to obtain an ethanol solution of 20% by mass of methyl methacrylate. The polypropylene separator was washed with acetone and dried at 60 ℃ for 6h. Then, the polypropylene diaphragm is soaked in ethanol solution of methyl methacrylate and sealed, and inert gas argon is introduced to remove dissolved oxygen (polymerization inhibition). The material is placed in a radiation field and irradiated by gamma rays, and the irradiation dose is 60kGy. After the irradiation, the irradiated polypropylene separator was rinsed with a large amount of ethanol to remove unreacted monomers and homopolymers. And then drying the membrane for 6 hours at 60 ℃ to obtain the modified polypropylene membrane after drying.
Example 7
Preparing a lyophilic modified diaphragm: 20g of poly (ethylene glycol) diacrylate (M n =250) was added to 80g of absolute ethanol and stirred at 500r/min for 6 hours to obtain an ethanol solution of poly (ethylene glycol) diacrylate with a mass fraction of 20%. The polypropylene separator was washed with acetone and dried at 60 ℃ for 6h. Then, the polypropylene diaphragm is soaked in ethanol solution of poly (ethylene glycol) diacrylate and sealed, and inert gas argon is introduced to remove dissolved oxygen (polymerization inhibition). The material is placed in a radiation field and irradiated by gamma rays, and the irradiation dose is 40kGy. After the irradiation, the irradiated polypropylene separator was rinsed with a large amount of ethanol to remove unreacted monomers and homopolymers. And then drying the membrane for 6 hours at 60 ℃ to obtain the modified polypropylene membrane after drying.
Example 8
Preparing a lyophilic modified diaphragm: 20g of poly (ethylene glycol) diacrylate (M n =250) was added to 80g of absolute ethanol and stirred at 500r/min for 6 hours to obtain an ethanol solution of poly (ethylene glycol) diacrylate with a mass fraction of 20%. The polypropylene separator was washed with acetone and dried at 60℃for 6 hours, and then the polypropylene separator was put into poly (ethylene glycol) diacrylate (M n =250), and then immersing and sealing the mixture in an ethanol solution, and introducing inert gas argon gas to remove dissolved oxygen (polymerization inhibition). The material is placed in a radiation field and irradiated by gamma rays, and the irradiation dose is 20kGy. After the irradiation, the irradiated polypropylene separator was rinsed with a large amount of ethanol to remove unreacted monomers and homopolymers. And then drying the membrane for 6 hours at 60 ℃ to obtain the modified polypropylene membrane after drying.
Examples 1-8 the irradiation grafting method used to prepare a modified membrane of high wettability was a co-irradiation grafting method.
Example 9
Preparing a lyophilic modified diaphragm: 20g of poly (ethylene glycol) diacrylate (M n =250) was added to 80g of absolute ethanol and stirred at 500r/min for 6 hours to obtain an ethanol solution of poly (ethylene glycol) diacrylate with a mass fraction of 20%. The polypropylene separator was washed clean with acetone and dried at 60 ℃ for 6h. Then, the polypropylene diaphragm is placed in a radiation field under the atmosphere of argon preservation to be pre-irradiated by gamma rays, and the irradiation dose is 10kGy. After the irradiation is finished, the pre-irradiated polypropylene diaphragm is soaked in an ethanol solution of poly (ethylene glycol) diacrylate and heated at 60 ℃ for reaction for 12 hours. And washing the polypropylene diaphragm after the grafting reaction by using a large amount of ethanol to remove unreacted monomers and homopolymers, and then drying the polypropylene diaphragm at 60 ℃ for 6 hours to obtain the modified polypropylene diaphragm. The irradiation grafting method employed in this example is a pre-irradiation grafting method.
Example 10
Preparing a lyophilic modified diaphragm: 20g of poly (ethylene glycol) diacrylate (M n =250) into 80g of absolute ethanol, stirring at a speed of 500r/minAfter stirring for 6 hours, an ethanol solution of 20% by mass of poly (ethylene glycol) diacrylate is obtained. The polyvinylidene fluoride-hexafluoropropylene separator was washed clean with acetone and dried at 60 ℃ for 6h. And then the polyvinylidene fluoride-hexafluoropropylene diaphragm is placed in a radiation field under the atmosphere of oxygen preservation to be pre-irradiated by gamma rays, wherein the irradiation dose is 10kGy. After the irradiation is finished, the pre-irradiated polyvinylidene fluoride-hexafluoropropylene diaphragm is soaked in an ethanol solution of poly (ethylene glycol) diacrylate, and the reaction is heated at 60 ℃ for 12 hours. Washing the polyvinylidene fluoride-hexafluoropropylene diaphragm after the grafting reaction by a large amount of ethanol to remove unreacted monomers and homopolymers, and then drying the diaphragm at 60 ℃ for 6 hours to obtain the modified polyvinylidene fluoride-hexafluoropropylene diaphragm. The irradiation grafting method employed in this example is a peroxidation method.
Example 11
A battery comprising a positive electrode material and a negative electrode material with the modified polypropylene separator prepared in example 1 therebetween.
Comparative example 1
A battery includes a positive electrode material and a negative electrode material with a common commercial polypropylene separator therebetween.
The battery cycle performance obtained in example 11 and comparative example 1 was tested as shown in fig. 4. It can be seen that the battery cycle performance of the modified separator obtained by using the present invention is significantly improved over that of a battery using a conventional separator of the prior art.
Example 12
A battery comprising a positive electrode material and a negative electrode material with the modified separator prepared in example 2 therebetween.
Example 13
A battery comprising a positive electrode material and a negative electrode material with the modified separator prepared in example 3 therebetween.
Example 14
A battery comprising a positive electrode material and a negative electrode material with the modified separator prepared in example 4 therebetween.
Example 15
A battery comprising a positive electrode material and a negative electrode material with the modified separator prepared in example 5 therebetween.
Example 16
A battery comprising a positive electrode material and a negative electrode material with the modified separator prepared in example 6 therebetween.
Example 17
A battery comprising a positive electrode material and a negative electrode material with the modified separator prepared in example 7 therebetween.
Example 18
A battery comprising a positive electrode material and a negative electrode material with the modified separator prepared in example 8 therebetween.
Example 19
A battery comprising a positive electrode material and a negative electrode material with the modified separator prepared in example 9 therebetween.
Example 20
A battery comprising a positive electrode material and a negative electrode material with the modified separator prepared in example 10 therebetween.
The foregoing description is only illustrative of the preferred embodiments of the present invention, and therefore should not be taken as limiting the scope of the invention, for all changes and modifications that come within the meaning and range of equivalency of the claims and specification are therefore intended to be embraced therein.

Claims (10)

1. A high wettability modified separator, characterized in that: the modified diaphragm is grafted with a lyophile monomer on the surface and/or in the holes of the diaphragm base material, and the lyophile monomer has lyophile functional groups.
2. The high wettability modified separator of claim 1, wherein: the lyophilic monomer has an unsaturated bond group and contains a functional group compatible similarly to the electrolyte.
3. The high wettability modified separator of claim 1, wherein: the lyophilic monomer comprises at least one of isobutyl vinyl ether, octadecyl vinyl ether, poly (ethylene glycol) diacrylate, methyl methacrylate, methyl acrylate, acrylonitrile, or 2,4,6, 8-tetramethyl-2, 4,6, 8-tetra-vinyl cyclotetrasiloxane.
4. The high wettability modified separator of claim 1, wherein: the membrane substrate comprises at least one of polyolefin porous polymer, non-woven fabric, polyethylene oxide, polyacrylonitrile, polymethyl methacrylate, polyvinylidene fluoride-hexafluoropropylene copolymer, polypropylene alcohol or polyimide.
5. A preparation method of a high-wettability modified diaphragm is characterized by comprising the following steps: the separator substrate is mixed with a lyophile monomer or an organic solution of lyophile monomer, and the lyophile monomer is grafted to the separator substrate by radiation grafting.
6. The method of manufacturing according to claim 5, wherein: the irradiation grafting method comprises a pre-irradiation grafting method, a co-irradiation grafting method or a peroxidation method.
7. The method of manufacturing according to claim 6, wherein: the pre-irradiation grafting method comprises the following steps: pre-irradiating the diaphragm base material in an anaerobic atmosphere, and then placing the diaphragm base material in the lyophilic monomer or the organic solution of the lyophilic monomer for grafting reaction; the co-irradiation grafting method comprises the following steps: placing the diaphragm substrate in the lyophilic monomer or the organic solution of the lyophilic monomer, and performing a grafting reaction by co-irradiation of a radiation source in an oxygen-free atmosphere; the peroxidation method comprises the following steps: and pre-irradiating the diaphragm base material in an oxygen atmosphere, and then placing the diaphragm base material in the lyophilic monomer or the organic solution of the lyophilic monomer for grafting reaction.
8. The method of manufacturing according to claim 5, wherein: the irradiation grafting dose is 10-200 KGy.
9. An application of a high-wettability modified diaphragm in a battery is characterized in that: the modified separator is a modified separator according to any one of claims 1 to 4, or a modified film produced by the production method according to any one of claims 5 to 8.
10. A battery comprising a positive electrode material and a negative electrode material, characterized in that: a high wettability modified separator according to any one of claims 1 to 4 between a positive electrode material and a negative electrode material, or a high wettability modified film produced by the production method according to any one of claims 5 to 8 between a positive electrode material and a negative electrode material.
CN202211042078.0A 2022-08-29 2022-08-29 High-wettability modified diaphragm and preparation method and application thereof Pending CN117673650A (en)

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